Lack of Bioequivalence When Levofloxacin and Calcium‐Fortified Orange Juice Are Coadministered to Healthy Volunteers

Chelation interactions between drugs/supplements that contain large amounts of multivalent ions and the fluoroquinolones have been known for quite some time. However, there has been a lack of taking this interaction into account when they may be coadministered with foods that have been fortified with amounts of multiple multivalent ions that equal or exceed many supplement products. A previous study demonstrated that 12 ounces of calcium-fortified orange juice significantly decreased the bioequivalence of a dose ofciprofloxacin. This study examined, in 16 healthy volunteers, whether 12 ounces of orange juice with and without calcium fortification would demonstrate the same chelation interaction with single doses of levofloxacin. The results of the study demonstrated that both types of juice decreased levofloxacin C max values by 14% to 18% and prolonged t max values by approximately 50%, with calcium-fortified orange juice decreasing C max enough to lose bioequivalence as compared to the control arm (89% [78.1%, 99.8%]). Due to the lack of change in overall exposure, it is thought that rather than a chelation interaction, levofloxacin and components of the orange juices competed for intestinal transport mechanisms such as P-glycoprotein and organic anion-transporting polypeptides, which resulted in the discovered interaction. These results further confirm the need to adjust regulatory studies to include bioequivalence/bioavailability studies that contain fortified foods more than high-calorie/high-fat foods to better reflect current American consumption habits.